In the US they are selling a towel-like material that is supposed to absorb (25x?) as much as a sponge. They have this LOUD salesman talking about it so I sure it out if it comes on one of the programs I am watching. Next time it comes on again I'll write it down and post it.

Yes, there also exists toys (a friend of me bought a little crocodile) made of cellulose, which absorbs a great amount of water becoming much bigger! I don't remember how much, maybe more than 100 times the initial weight.She put that little crocodile (~10 cm) in the bath tube and after some hours it became half a metre!